What is the difference between the following bulb sockets: b8.5d, b8.4d and bx8.4d? Are they interchangeable? (And especially, what's the difference with the x and non-x version?)
Background: I need to replace the lighting on the dashboard (Opel Astra G, in case that matters), and various sources provide different light bulb types (and I did not find much about the topic, after repeated searches).



